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Author Topic: Electrics keep tripping since Solar PV install  (Read 1026 times)
geezer
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« on: September 17, 2017, 10:05:52 AM »

Hi, Since my Solar PV has been installed, my mains electricity keeps tripping , seemingly totally randomly.  Sometimes it'll be fine for a couple of weeks or so, then other times it might trip 3 or 4 times in a single day.  Occasionally there is resistance to flipping the switch back on, other times not. It seems to happen mostly when there is hardly any PV electric being produced, early in the morning, late at night, although sometimes during the day.

My installer reckons that my house mains board RCD may be on the way out.  So I'm getting an electrician to check this.  Does any one have any idea what could be causing this?

Set up is:

4.2kw JA Solar  panels set up on back garden wall, to Solis inverter on back wall of shed (protected from the weather) running through RCD powering the shed/office., 45amp Shielded cable running 50m to mains board at front of house. Solic hot water device fitted next to mains distribution board.

I have switched off the power to the Solic Hot water unit but this makes no difference to the tripping.  The power never trips off at the shed/top of garden, it is always on the Mains board to the house and it is always the main switch that trips, never individual circuits.

It is so random that we have stopped using our freezer. Any opinions would be welcome. thanks
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eabadger
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« Reply #1 on: September 17, 2017, 10:17:57 AM »

hello, and welcome to Navitron.
you need an electrician to test your rcd tripping times, any electrician should have suitable testing equipment.
however we had random tripping on our off grid settup which was down to the type of RCD fitted, i swapped my rcds out for type A devices instead of the standard type AC, we have now no more intermittent trips, maybe worth discussing with the electrician.

steve
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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
Countrypaul
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« Reply #2 on: September 17, 2017, 10:36:42 AM »

You're description suggests that the inverter is quite a long way from the CU. Does the inverter log show any issues? I am just wondering if because of the distance you might be getting a higher voltage than you should have causing other issues leading to the tripout. You'll have to ask your electrician to check, but you might be able to check the log on the inverter yourself.

You describe the cable as 45Amp, do you know what cross section the wires are, 2.5mm2, 4mm2 or 6mm2 presumeably it is armoured?
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eabadger
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« Reply #3 on: September 17, 2017, 10:46:32 AM »

if the inverter is transformerless, the dc waveform they inject may be the issue, here in France type AC rcd are only allowed on resitive loads such as the immersion all others must be type A, doing a quick google Uk is one of the only countries still using type AC as standard, and again google referring to intermittent tripping on solar installs on type AC.

best get a competent electrician to test and advise.

steve
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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
geezer
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« Reply #4 on: September 17, 2017, 10:54:23 AM »

Thank you very much for your prompt replies guys, as you can imagine this is causing a real headache.

I will definitely flag up your comments to the electrician next week when he calls round.

I am using 6mm armoured cable on my 45amp run back to the mains board.
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Westie
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« Reply #5 on: September 17, 2017, 11:10:31 AM »

After our PV was installed we had frequent RCD trips, mainly on cold sunny days when output was high.  The whole house was protected by a single 30mA RCD fitted between the meter and the CU.

Reading the Inverter manual SMA recommended the RCD was 100mA!  I think 100mA leakage tolerance is too high so I replaced  the 'whole house' 30mA RCD with a 80A MCB then fitted 30mA RCBOs on the ring mains in place of the MCBs. The inverter feeds into the CU thro an MCB.  No problems since.

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4kwp south facing array  SMA 4000TL grid connected.  2x30tube Navitron solar thermal panels (east/west). Arada 5kw S/C WBS. KTM E-Bike  Cool
eabadger
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« Reply #6 on: September 17, 2017, 11:18:17 AM »

could it have been the "clipping" when high output? did you fit standard (uk) type AC?
http://www.circuit-protection.co.uk/latest-news/120-solar-power-installations--do-you-know-what-type-of-rccb-to-use-and-why

seems to say type B, but given a search on that shows aus and nz regs disregard them and the cost, all seem to point to B or A, definitely not type AC.
never seen a type B here, i will inquire when in CEF/Yesff or whatever it is called now.

steve
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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
geezer
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« Reply #7 on: September 17, 2017, 05:40:57 PM »

Thanks for all your help, the link is very helpful.  I'm beginning to feel a lot more optimistic!  I'll keep you posted.
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Stugadget
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« Reply #8 on: October 11, 2017, 06:33:31 PM »

Hi

When I install transformer-less inverters I never put them on an RCD as this is a known issue. I always install the cable on the surface therefore RCD protection is not required unless you have TT earthing arrangements then I would put it on its own consumer unit projected by a 100ma RCD.

Stu.
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rogeriko
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« Reply #9 on: October 11, 2017, 10:21:26 PM »

A 30ma RCD will trip with solar PV. Your electrician must find a way of connecting the inverter bypassing the 30ma RCD but maintaining the legality of the house installation. (common problem)
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Scruff
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« Reply #10 on: October 11, 2017, 10:30:57 PM »

What's acceptable practice to achieve that R?
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eabadger
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« Reply #11 on: October 12, 2017, 08:07:01 AM »

standard uk RCD is not compliant with PV install, should have been changed by installer part of the sign off.
why do the uk still fit type AC as standard?
UK Regs say type B for pv. but type A work fine and are used on mainland europe pretty much as standard.
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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
RIT
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« Reply #12 on: October 12, 2017, 03:37:54 PM »

What's acceptable practice to achieve that R?

A common solution is to install a henley block between the meter and the CU, this allows the PV output to be upstream of the CU's RCD. It also seems that its common practice to now install a 100ma RCD between the meter and the henley block as additional protection for the PV circuit.

I've no idea what the current rules are for henley blocks when an additional general spur is installed such as the configuration that the OP describes. As with all things electrical you need to find a current competent electrician and put the idea forward to hear what they say. The only real issue is the small matter of finding a competent electrician.
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Why bother? - well, there is no planet B
rogeriko
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« Reply #13 on: October 12, 2017, 03:58:56 PM »

What's acceptable practice to achieve that R?

The easiest way is to add a second consumer unit just for the PV right up against the existing unit. You can spur off the incoming mains.
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eabadger
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« Reply #14 on: October 12, 2017, 04:34:32 PM »

does not really change the issue the ma rating it is the induced dc that is the probable issue, op has not responded if the correct type was fitted at installation time, but i suspect not.
bosch washing machines also trip standard uk rcd's, and is mentioned in the owners manual.

steve
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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
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